scholarly journals On the Surface Settlement and Lining Stress of Shield Tunnel in Sand Observed in a Centrifuge.

1997 ◽  
pp. 283-293
Author(s):  
Toshi Nomoto ◽  
Shinichiro Imamura
Keyword(s):  
Surface Settlement ◽  
Shield Tunnel

Surface Settlement and Influence on Xi’an City Wall due to Xi’an Subway Line 2 Tunnel Construction

2011 ◽  
Vol 374-377 ◽  
pp. 2326-2332
Author(s):  
Jun Lian Li ◽  
Jian Guo Zheng ◽  
Yang Ping Yao
Keyword(s):  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
The South ◽  
Protective Measures ◽  
City Wall ◽  
Calculation Results ◽  
Settlement Ratio ◽  
Grouting Reinforcement ◽  
Xi’An City

This paper refers the case project of the Xi'an Subway Line 2 tunneling through the South Gate area of the Xi'an City Wall, has researched the surface settlement due to tunnel construction, and simulated the whole shield tunnel by using Flac3D numerical analysis. This paper has obtained the law of surface settlement and the influence on the City Wall in the tunnel construction by analyzing the calculation results, and simulated the effects of three protective measures which will be used in the South Gate area. The results showed that the surface settlement ratio after the piles and chemical grouting reinforcement was lower by about 25% than no reinforcement. The monitoring data showed that the result of model calculation was reasonable, and the protective measures in Condition 3 are feasible and effective.

Prediction of Shield Tunnelling-Induced Ground Settlement Considering Soil-Water Coupled and around Soil Disturbance Damage

2010 ◽  
Vol 168-170 ◽  
pp. 357-364
Author(s):  
Ji Feng Liu ◽  
Bo Liu ◽  
Hui Zhi Zhang
Keyword(s):  
Numerical Simulation ◽  
Soil Water ◽  
Ground Surface ◽  
Soil Disturbance ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Ground Settlement ◽  
Ground Surface Settlement ◽  
Shield Tunnelling

to evaluate the influence of soil-water coupled and shield tunnel construction induced around soil disturbance damage on ground surface settlement, the process of shield tunnel construction induced around soil disturbance is analyzed, the FLAC3D numerical simulation are carried out, and a newly-modified tunnelling-induced ground settlement calculation method based on disturbance degree of around soil and soil-water coupled is presented, and these methods are applied in case of Beijing Metro 10thLine. It is indicated that considering the influence of the shield tunnelling-induced around soil disturbance damage, and soil-water coupled induced soil properties weakening and the excess pore water pressure dissipating induced soil consolidation to the ground surface settlement are necessary, the calculating result of the newly-modified surface settlement prediction method, and the result FLAC3D numerical simulation all agree well with in-site observed data of Beijing Metro 10th Line.

Surface Settlement Law Induced by Shield Tunnel Excavation Using Modified Gap Model

2012 ◽  
Vol 170-173 ◽  
pp. 1515-1519
Author(s):  
Wen Bo Li ◽  
Wen Pei Wang ◽  
Lian Jin Tao ◽  
Yin Tao Zhang
Keyword(s):  
Critical Value ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Gap Model ◽  
Tunnel Excavation ◽  
Maximum Settlement ◽  
Maximum Surface ◽  
Adjacent Buildings ◽  
Maximum Surface Settlement ◽  
Tunnel Depth

GAP model will be modified and programmed by FISH language, which can be used in FLAC2D programs. The modified GAP model is used to study the variation of surface settlement shape with depth, the variation of the maximum settlement value with depth, and the variation of settlement gradient with depth. The results show that: the settlement shape is narrow and deep with the conditions of shallow buried depth of tunnel; on the contrary, the settlement shape is wide and shallow; When the tunnel depth is less than the critical value, the tunnel depth and the maximum surface settlement is approximately linear; when the tunnel depth is greater than the critical value, the curve of maximum surface settlement value with depth becomes flat and with the increase of the tunnel, the surface settlement gradient gradually decreases and eventually tends to zero. It is more reasonable to assess the influence of tunnel excavation near adjacent buildings, using the maximum surface settlement and the settlement gradient as a control standard.

Finite Element Analysis of the Surface Settlement Induced by the Shield Tunnel Construction

2014 ◽  
Vol 501-504 ◽  
pp. 111-114
Author(s):  
Ling Xia Gao ◽  
Xiang Jun Yang ◽  
Li Kun Qin
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Three Dimensional ◽  
Longitudinal Direction ◽  
Element Model ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Empirical Formulas ◽  
Element Analysis ◽  
Polynomial Expression

Three-dimensional non-linearity finite element model of shield tunnel was established on basis of the Z1 line of Tianjin subway. And then it was applied to simulate construction process of shield tunnel. Surface settlement of the tunnel during the construction was obtained. The settlement data of transverse and longitudinal direction from numerical simulation were fitted through a polynomial expression. Then a contrastive analysis of curves from numerical simulation and matching formulae were made. The result shows that it is feasible to utilize the empirical formulas like Pecks to predict surface settlement in Tianjin caused by shield construction.

GA-NN Monitoring Model and its Application on Surface Settlement

2012 ◽  
Vol 505 ◽  
pp. 453-457
Author(s):  
Tie Sheng Wang ◽  
Hai Yan Li ◽  
Bing Zhang ◽  
Kai Feng Ma
Keyword(s):  
Neural Network ◽  
Influence Factors ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Excavation ◽  
Monitoring Model ◽  
Efficiency And Effectiveness ◽  
Genetic Neural Network ◽  
Set Up ◽  
Under Construction

Combining the advantages of basic genetic algorithm and neural network, analyze and set up GA & NN genetic neural network, explore and study the algorithm. The efficiency and effectiveness of this hybrid training has been significantly improved comparing with the single genetic evolution or BP training method, its versatility is better. The model is applied to predict the deformation of shield tunnel excavation. According to the effects of measured influence factors under construction, it can make the appropriate forecast to the surface settlement which is better than the conventional regression model. It shows that neural networks in the ground during tunneling shield analysis and prediction of settlement is practical and adaptable.

scholarly journals Slurry shield tunneling in soft ground. Comparison between field data and 3D numerical simulation

2019 ◽  
Vol 41 (3) ◽  
pp. 115-128
Author(s):  
Mohammed Beghoul ◽  
Rafik Demagh
Keyword(s):  
Urban Areas ◽  
Ground Surface ◽  
Injection Pressure ◽  
Tunnel Boring Machine ◽  
Surface Settlement ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Ground Movements ◽  
Ground Surface Settlement

Abstract In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.

scholarly journals Investigation on the Surface Settlement for Curved Shield Construction in Sandy Stratum with Laboratory Model Test

2021 ◽  
Author(s):  
Ping Xu ◽  
Danhui Xi
Keyword(s):  
Similarity Theory ◽  
Surface Settlement ◽  
Small Radius ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Curvature Radius ◽  
Small Curvature ◽  
Practical Engineering ◽  
Turning Radius ◽  
Laboratory Model Test

Abstract According to the existing practical engineering data, the settlement curve of shield tunnel with small curvature radius is obviously different from that of straight tunnel, so using Peck formula to forecast the surface settlement is not applicable. This paper describes results from a series of the laboratory test based on similarity theory carried out in sandy soil. According to the test results, the characteristics of surface settlement caused by small radius tunnel excavation are summarized, and the effects of turning radius and buried depth on the surface settlement are demonstrated. Based on Gaussian formula, a method to forecast the surface settlement caused by construction of shield tunnel with small curvature radius is developed.

scholarly journals Numerical Study on the Disturbance Effect of Short-Distance Parallel Shield Tunnelling Undercrossing Existing Tunnels

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zhen Huang ◽  
Chenlong Zhang ◽  
Helin Fu ◽  
Huangshi Deng ◽  
Shaokun Ma ◽  
...  
Keyword(s):  
Numerical Model ◽  
Short Distance ◽  
Maximum Stress ◽  
Numerical Study ◽  
Soil Layer ◽  
Field Monitoring ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Double Line ◽  
Shield Tunnelling

The construction of new tunnels poses a threat to the operational safety of closely existing tunnels, and the construction mode of parallel undercrossing over short distances has the most significant impact. In this study, a new double-line shield tunnel parallel undercrossing of existing tunnels in Hefei, China, is taken as an example. A three-dimensional (3D) numerical model using FLAC3D finite difference software was established. The dynamic construction of the new double-line shield tunnel undercrossing the existing subway tunnel over a short distance and in parallel was simulated. The pattern of existing tunnel settlement and change in lining stress caused by the shield tunnelling process were analyzed. The reliability of simulation was verified through field-monitoring data. Finally, based on the numerical model, the effects of change in stratum sensitivity on the settlement of existing tunnel, lining internal force, and surface settlement are discussed. The results show that during shield tunnelling, the maximum ground settlement is 3.9 mm, the maximum settlement at the arch waist of existing tunnel near the new tunnel is 7.75 mm, and the maximum vault settlement is 5.38 mm. The maximum stress of lining of existing tunnel before the excavation is 7.798 × 105 Pa. After the construction of double-line shield tunnel, the maximum stress of lining is 1.124 × 106 Pa, an increase of 44% than that before the construction. The surface settlement and tunnel settlement are sensitive to the weakening of soil layer strength, and lining stress is not affected by the weakening of soil layer strength. The field-monitoring results are consistent with the numerical simulation results, and the model calculation is reliable. This study plays an important role in ensuring construction safety and optimizing the construction risk control of a tunnel.

scholarly journals Spatial Variability of Grouting Layer of Shield Tunnel and Its Effect on Ground Settlement

2020 ◽  
Vol 10 (14) ◽  
pp. 5002
Author(s):  
Zhongzheng Wang ◽  
Dalong Jin ◽  
Chenghua Shi
Keyword(s):  
Spatial Variability ◽  
Negative Impact ◽  
Ground Surface ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Spatial Characteristics ◽  
Ground Surface Settlement ◽  
Prediction Approach

This study aims to investigate the effect of the spatial variability of grouting-layer thickness on ground-surface settlement caused by shield tunneling and to provide a rational prediction method. The spatial characteristics of grouting layers were obtained based on statistical analysis. The random finite element method was used to study the effect of spatial variability of different parameters on ground-surface settlement. Simulation results indicate that the spatial variability of the grouting layer has a negative impact on ground settlement. The surface settlement will be underestimated without considering the spatial characteristics of the grouting layer. Thus, a reliable prediction approach of the maximum ground settlement was proposed to control the construction quality.

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